Electrostatic charges can interfere with manufacturing processes, such as those used in the electronics industry where uncontrolled electrostatic discharge can result in the damage of products being manufactured. Additionally, manufacturing facilities which currently are prone to electrostatic damage of the products being made have developed comprehensive procedures, equipment and methods to combat the buildup and uncontrolled transfer of electrostatic charge. In addition the introduction of energy weapons as a means of incapacitating an individual has triggered the need for apparel formed from fabric that can transmit a high electrical charge. Additionally, law enforcement personnel and other individuals use electronic control devices (e.g.,“stun guns” such as those made by and available from TASER of Scottsdale, Ariz. or similar devices), hereinafter referred to as “stun guns,” to subdue individuals. The advent of individuals being allowed to buy stun gun technology results in a need for law enforcement personnel to have a means to counteract that threat. Therefore a means to protect both manufacturers from losses due to electrostatic discharge and law enforcement personnel from stun guns is needed. The solution to electrostatic discharge and energy weapon attacks requires that the materials used or worn are capable of dissipating a significant electrical charge to protect either personnel or product. Additionally many applications exist for a highly conductive three dimensional material such as a conductive fabric that has excellent lubricity and wear resistance. Examples of devices that could benefit from such a material are contact angular motion detectors or slides for measuring distance for use on equipment.
Prior techniques have addressed this problem by incorporating a small quantity of conductive fibers in the textile fiber material or the backing component of the fabric to act as a static dissipation element. For example, U.S. Pat. No. 4,756,941 to McCullough et al. discloses an electro-conductive tow or yarn made from continuous filaments or staple fiber yarns. The yarns are prepared from stabilized petroleum pitch, coal tar pitch or a synthetic fiber forming material which, on at least partial carbonization, is electro-conductive. The yarns are formed into coil-like fibers or filaments by winding the tow or yarn into a cloth, and heat treating the thus formed tow or yarn to a carbonizing temperature to set a coilure therein as well as electro-conductive properties thereto. McCullough et al. describe the use of a blend of nylon and conductive fibers to form a web which is then needle punched onto a polypropylene spun-bonded backing to give a conductive carpet.
U.S. Pat. No. 4,557,968 to Thornton, et al. describes a directional electrostatic dissipating fabric and method of making such fabric constructed of a woven or knitted base fabric having an integrally woven or knitted grid structure which is raised above only one surface of the base fabric forming a fabric with a raised grid on one side and a smooth or substantially smooth grid on the other side thereby resulting in increased, directional electrostatic dissipation performance from the side having the raised grid. The grid is formed from an electro-conductive yarn plied to a carrier yarn which is then integrally woven or knitted into the fabric in the warp direction, the fill direction or both, thereby producing a fabric which exhibits the rapid, yet controlled, directional dissipation of static electricity into the air. Such fabric can be used for anti-static covering cloths, filtration media and the like; but is particularly adapted for use in anti-static garments and it is particularly comfortable when the smooth or substantially smooth surface is adjacent to the wearer and the raised surface is on the outside of the garment.
U.S. Pat. No. 5,368,913 to Ortega describes antistatic spun-bonded non-woven fabrics. The fabrics of the invention include a plurality of substantially continuous electrically nonconductive filaments formed of a thermoplastic polymer, a plurality of electrically conductive filaments distributed among the electrically nonconductive filaments throughout the fabric, and a multiplicity of discrete bond sites bonding together the electrically nonconductive and the electrically conductive filaments to form a coherent fabric.
U.S. Pat. No. 6,794,475 to Bialke, et al. describes antistatic polymers, blends, and articles. U.S. Pat. No. 3,955,022 to Sands describes a primary carpet backing comprising a woven or bonded non-woven sheet of continuous filaments having needled thereto a layer of a blend of staple fibers. The staple fibers include a synthetic organic polymeric fiber containing conductive carbon.
U.S. Pat. No. 6,656,388 to Yang, et al. describes a processable electrically conductive polymeric complex comprising a polyelectrolyte having acid functional groups and a conductive polymer. However, he states that electronic conductors are difficult to dye.
Despite these and other techniques for forming an antistatic fabric and conductive fabrics that are capable of carrying an electrical charge, a fabric having the ability to provide substantially uniform distribution of the conductive fibers throughout is desirable, so as to provide good electrical dissipation and transfer properties. This would in turn reduce the need for using antistatic chemicals, woven threads or other additives in the fabric to provide electrical conductivity. Further, it would be desirable to provide a fabric having conductive fibers which are an integral part of the article and not polymer based or specially woven with conductive fibers so that the article is comfortable to wear and provides excellent conductive properties. An added advantage would be to provide a fabric that has low coefficient of friction so that when used in applications where the fabric is in contact with mechanical sliding components the friction coefficient is not high.